Effects and Mechanisms of Acupuncture and Moxibustion on Reproductive Endocrine Function in Male Rats with Partial Androgen Deficiency

2016 ◽  
Vol 34 (2) ◽  
pp. 136-143 ◽  
Author(s):  
Yi Ren ◽  
Xiaoguang Yang ◽  
Yu Zhang ◽  
Ying Wang ◽  
Xuezhi Li
Keyword(s):  
Protein Expression ◽  
Mrna Expression ◽  
Serum Testosterone ◽  
Hydroxysteroid Dehydrogenase ◽  
Endocrine Function ◽  
Male Rats ◽  
Acupuncture Points ◽  
Total Testosterone ◽  
Androgen Deficiency ◽  
Serum Lh

Objectives Partial androgen deficiency of the aging male (PADAM) is characterised by a deficiency in serum androgen levels. Both electroacupuncture (EA) and mild moxibustion (MM) can raise serum testosterone levels in PADAM. We investigated the mechanisms underlying the use of EA and MM in a rodent model of PADAM. Methods Fifty rats received cyclophosphamide injection over 5 consecutive days to induce PADAM, which was verified by comparing total testosterone (TT) and free testosterone (FT) levels with 10 non-PADAM healthy control rats (CON). Successful modelling was confirmed in 43 of 50 rats, 40 of which were randomly divided into untreated (PADAM), EA-treated (PADAM+EA), MM-treated (PADAM+MM), and androlin (AD)-treated (PADAM+AD) groups (n=10 each). EA and MM were administered at BL23 and CV4 acupuncture points for 8 weeks, and no treatment was given to rats in the PADAM and CON groups. Serum levels of luteinising hormone (LH) and follicle-stimulating hormone (FSH), mRNA expression of cytochrome P450c17 (P450c17) and 3β-hydroxysteroid dehydrogenase 1 (3β-HSD1), and protein levels of cytochrome P450 side chain cleavage (P450scc), 17β-hydroxysteroid dehydrogenase 3 (17β-HSD3) and steroidogenic factor 1 (SF-1) were evaluated after 8 weeks. Results Both EA and mild MM significantly increased serum TT and FT levels with MM displaying superiority. P450scc, 17β-HSD3 and SF-1 protein expression, and P450c17 and 3β-HSD1 mRNA expression, were significantly increased and serum LH and FSH levels were significantly decreased in PADAM+EA and PADAM+MM relative to PADAM rats. Moreover, serum LH and FSH levels were significantly lower and 17β-HSD3 protein expression significantly higher in PADAM+MM relative to PADAM+EA rats. Conclusions EA and MM at the BL23 and CV4 acupuncture points appear to be effective treatments for PADAM, and MM displays superior efficacy to EA.

Pituitary–testicular interrelationships during germinal involution in the vitamin A deficient rat

1984 ◽  
Vol 100 (1) ◽  
pp. 33-41 ◽  
Author(s):  
H. F. S. Huang ◽  
P. Zaidi ◽  
E. Nieschlag
Keyword(s):  
Vitamin A ◽  
Vitamin A Deficiency ◽  
Serum Testosterone ◽  
Normal Serum ◽  
Male Rats ◽  
Total Testosterone ◽  
Cell Nuclei ◽  
Serum Lh ◽  
Testicular Weight ◽  
Lh Secretion

ABSTRACT Pituitary–testicular relationships in mature male rats were investigated during the period of germinal involution after the induction of vitamin A deficiency (VAD). Vitamin A deficiency caused a decrease in testicular weight, a gradual increase in the incidence of delayed spermiation, increased phagocytosis of spermatids and pyknosis of germ cell nuclei in rats aged 80 to 110 days. Both basal and gonadotrophin releasing hormone (GnRH)-stimulated serum FSH concentrations were increased by 100 days of age. During the same period, the per cent increment in GnRH-stimulated FSH secretion, pituitary FSH concentration and LH secretion remained unchanged. These results suggest that the increased serum FSH may mark specifically an alteration in the germinal epithelium. By 140 days of age, spermatogenic activity in the rats with VAD was limited to the spermatogonial proliferations so that only Sertoli cells, spermatogonia and preleptotene spermatocytes remained. At this time hypersecretion of FSH persisted while the per cent increment of GnRH-stimulated FSH secretion decreased. Concomitantly, basal and GnRH-stimulated LH concentrations were also increased in the presence of normal serum testosterone. These results indicate that a complete cessation of spermatogenesis beyond preleptotene spermatocytes is associated with a change in the secretion of both FSH and LH. The relationship between serum LH and testosterone was normal until at least 110 days of age. By 140 days the ratio between basal LH and basal testosterone, and between total LH and total testosterone, after GnRH administration, increased in the rats with VAD. These changes may be caused by a hyporesponsiveness of the Leydig cells which may, in turn, be attributed to the cessation of spermatogenesis. J. Endocr. (1984) 100, 33–41

scholarly journals Common and specific effects of the two major forms of prolactin in the rat testis

2007 ◽  
Vol 293 (6) ◽  
pp. E1795-E1803 ◽  
Author(s):  
Valencia L. Williams ◽  
Ariel DeGuzman ◽  
Hong Dang ◽  
Mitsumori Kawaminami ◽  
Timothy W. C. Ho ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Fas Ligand ◽  
Regulatory Protein ◽  
Specific Effect ◽  
Serum Testosterone ◽  
Hydroxysteroid Dehydrogenase ◽  
Luteinizing Hormone Receptor ◽  
Male Rats ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Specific Effects

Prolactin (PRL) has both stimulatory and inhibitory effects on testicular function, a finding we hypothesized may be related in some part to the form of the hormone present or administered. In the analysis of the pituitary secretion profiles of early pubescent vs. mature male rats, we found PRL released from early pubescent pituitaries had about twice the degree of phosphorylation. Treatment of mature males with either unmodified PRL (U-PRL) or phosphorylated PRL (via the molecular mimic S179D PRL) for a period of 4 wk (circulating level of ∼50 ng/ml) showed serum testosterone decreased by ∼35% only by treatment with the phospho-mimic S179D PRL. Given the specificity of this effect, it was initially surprising that both forms of PRL decreased testicular expression of 3β-hydroxysteroid dehydrogenase and steroidogenic acute regulatory protein. Both forms also increased expression of the luteinizing hormone receptor, but only S179D PRL increased the ratio of short to long PRL receptors. Endogenous PRL and luteinizing hormone levels were unchanged in all groups in this time frame, suggesting that effects on steroidogenic gene expression were directly on the testis. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling analysis combined with staining for 3β-hydroxysteroid dehydrogenase and morphometric analysis showed that S179D PRL, but not U-PRL, increased apoptosis of Leydig cells, a finding supported by increased staining for Fas and Fas ligand in the testicular interstitium, providing an explanation for the specific effect on testosterone. S179D PRL, but not U-PRL, also increased apoptosis of primary spermatogonia, and U-PRL, but not S179D PRL, decreased apoptosis of elongating spermatids. Thus, in mature males, hyperprolactinemic levels of both forms of PRL have common effects on steroidogenic proteins, but specific effects on the apoptosis of Leydig and germ cells.

Acute and short-term actions of serotonin administration on the pituitary-testicular axis in the adult rat

1995 ◽  
Vol 7 (5) ◽  
pp. 1101 ◽  
Author(s):  
MP Hedger ◽  
S Khatab ◽  
G Gonzales ◽  
Kretser DM de
Keyword(s):  
Serum Testosterone ◽  
Fold Increase ◽  
Significant Inhibition ◽  
Male Rats ◽  
Minor Role ◽  
Testis Weight ◽  
Serum Concentrations ◽  
Adult Rat ◽  
Serum Lh ◽  
A Minor

In this study, adult male rats were injected intraperitoneally with a single dose of serotonin (5-hydroxytryptamine, 5HT; 10 mg kg-1 bodyweight) for 2 h or 18 h, or daily with graded doses of 5HT (0.1-10 mg kg-1) for four days before being killed. Serum and testicular interstitial fluid (IF) concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone and immunoreactive-inhibin were measured by radioimmunoassay, and one testis was removed for histological examination. At 2 h after a single injection, 5HT caused a significant inhibition of serum concentrations of LH and inhibin, recovered IF volume and intratesticular testosterone concentrations; testis weight and serum concentrations of testosterone and FSH were unaffected. At 18 h after injection, all parameters had returned to normal, with the exception of intratesticular testosterone concentration which remained lower than normal. The lowest 5HT dose (0.1 mg kg-1) had no effect on any parameter following four daily injections. At a dose of 1.0 mg kg-1 5HT, there was a four-fold increase in the concentration of serum LH, but testis weight, recovered IF volume, testosterone and inhibin concentrations and serum concentrations of FSH were not significantly affected. At the highest dose of 5HT (10 mg kg-1) after four daily injections, testis weight decreased, and IF volume increased nearly three-fold. Testis concentrations of inhibin and serum testosterone were reduced, whereas serum concentrations of both LH and FSH were elevated; intratesticular testosterone concentrations did not differ from controls. Only at the highest dose of 5HT was disruption to the seminiferous epithelium observed, with focal damage ranging in severity from increased degeneration of spermatogenic cell profiles, to complete loss of the germinal epithelium; however, many tubule profiles displayed completely normal spermatogenesis. The acute IF volume reduction and spermatogenic disruption in 5HT-treated rats were consistent with localized ischaemia due to constriction of the testicular arterial supply. The eventual increase in IF volume observed after 5HT treatment appeared to be secondary to the loss of germ cells. Although 5HT also inhibited pituitary LH release and Leydig cell steroidogenesis, these effects appeared to play only a minor role in the induction of spermatogenic damage.

scholarly journals Androgen Deficiency and Erectile Dysfunction in Patients with Type 2 Diabetes

2015 ◽  
Vol 8 ◽  
pp. CMED.S27700 ◽  
Author(s):  
Entesar O.A. El Saghier ◽  
Salah E. Shebl ◽  
Olfat A. Fawzy ◽  
lhab M. Eltayeb ◽  
Lamya M.A. Bekhet ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Erectile Dysfunction ◽  
Hypogonadotropic Hypogonadism ◽  
Multivariate Logistic Regression Analysis ◽  
Serum Testosterone ◽  
Total Serum ◽  
Total Testosterone ◽  
Androgen Deficiency ◽  
Cross Sectional

Background The association between type 2 diabetes mellitus (T2DM) and low total serum testosterone (LST) has been identified in several cross-sectional studies. Objectives To assess the prevalence of androgen deficiency and erectile dysfunction (ED) and their relation to glycemic control within a sample of Egyptian men with T2DM. Research Design and Methods A cross-sectional study including 70 men having T2DM. Their ages ranged from 30 to 50 years. They were evaluated for symptoms of androgen deficiency and ED, using a validated Arabic-translated Androgen Deficiency in Aging Males questionnaire and five-items version of the International Index of Erectile Function-5, respectively. Total testosterone (TT), glycated hemoglobin (HbA1c), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin were measured for all study subjects. Penile hemodynamics was assessed using penile duplex study for subjects who gave history of ED. Results LST was found in 40% of studied men, and 92.9% of them reported overt symptoms of androgen deficiency. ED was detected in 85.7% of those with LST, as opposed to 31.0% of those with normal TT ( P < 0.000). TT was lower in diabetic men with ED compared to those without ED (12.04 ± 5.36 vs 17.11 ± 7.11 nmol/L, P < 0.001). Significant negative correlation was found between TT and age, body mass index, waist circumference, systolic and diastolic blood pressures, and HBA1c ( P < 0.00). FSH, LH, and prolactin levels were within the normal reference range in all subjects. HbA1c was higher in patients who had LST with ED, compared to those with normal TT and without ED. However, multivariate logistic regression analysis did not reveal a significant association between HBA1c and LST levels. Conclusion LST, symptoms of androgen deficiency, and ED are common in the studied sample of Egyptian men with T2DM. Inappropriately normal FSH and LH in face of LST may denote a state of hypogonadotropic hypogonadism. HBA1c was found to be more significantly associated with ED than with LST.

HYPOTHALAMIC-PITUITARY-TESTICULAR SYSTEM FOLLOWING TESTICULAR X-IRRADIATION

1976 ◽  
Vol 83 (1) ◽  
pp. 190-200 ◽  
Author(s):  
H. L. Verjans ◽  
K. B. Eik-Nes
Keyword(s):  
Interstitial Cell ◽  
Serum Testosterone ◽  
Male Rats ◽  
Ventral Prostate ◽  
Testis Weight ◽  
X Ray ◽  
Serum Lh ◽  
Testicular Weight ◽  
Unknown Factor ◽  
X Irradiation

ABSTRACT Testes of adult, male rats were exposed to a total dose of 1500 R of X-irradiation. Testicular weight decreased from day 8 after X-ray treatment. This decrease was, however, preceded by an increment of the testis weight on day 4 following treatment. X-ray treatment of testes was associated with significant increases in serum FSH. Testicular irradiation had, however, no effect on ventral prostate and seminal vesicles weights. Serum testosterone increased only on day 1, 2 and 4 after irradiation, while serum LH levels tended to increase from day 8 post-irradiation. These changes were not significant, however, when compared with non-irradiated controls. At 7, 13 and 20 days following 1500 R of bilateral, testicular X-irradiation, the hypothalamic-pituitary unit was still capable of responding to exogenous gonadotrophin releasing factor. Serum FSH may in male rats be regulated at least partly by circulating steroids of testicular origin and partly by an unknown factor of non-interstitial cell nature.

The contribution of corticosterone and testosterone to the suppression of serum LH in hyperprolactinaemic adult male rats with pituitary transplants

1987 ◽  
Vol 113 (1) ◽  
pp. 111-116 ◽  
Author(s):  
R. F. A. Weber ◽  
M. P. Ooms ◽  
J. T. M. Vreeburg
Keyword(s):  
Adult Male ◽  
Serum Testosterone ◽  
Serum Levels ◽  
Male Rats ◽  
Male Rat ◽  
Serum Concentrations ◽  
Testosterone Secretion ◽  
Accessory Sex Glands ◽  
Serum Lh ◽  
Stimulation Of

ABSTRACT The effects of hyperprolactinaemia on serum levels of LH were investigated in adult male rats of the R × U strain. Hyperprolactinaemia was induced by three pituitary grafts under the kidney capsule, transplanted on day 0 of each experiment. Special attention was paid to the contribution of prolactin-stimulated testes, adrenals and corticosterone. In experiment 1, hyperprolactinaemia significantly reduced the serum concentrations of LH in intact rats. In spite of a significant increase in the serum levels of corticosterone, serum testosterone was not significantly affected by hyperprolactinaemia. The weights of both the adrenals and accessory sex glands were significantly increased at autopsy. In experiment 2, treatment with 10 mg corticosterone s.c. daily from day 14 to day 28 after pituitary grafting significantly reduced serum levels of both LH and testosterone. The suppression of testosterone in the hyperprolactinaemic corticosterone-treated animals was significantly less than in the corticosterone-treated control animals. The weights of the accessory sex glands were significantly increased in the hyperprolactinaemic animals. In experiment 3, rats were adrenalectomized and half of them were substituted with corticosterone. Serum testosterone levels significantly increased in both hyperprolactinaemic adrenalectomized rats and in adrenalectomized corticosterone-treated animals without any significant effect on serum LH. Again the weights of the accessory sex glands were significantly increased in the hyperprolactinaemic animals. In experiment 4, rats were adrenalectomized, gonadectomized and corticosterone treated on day 0 and then implanted with a 2, 1·5 or 1 cm silicone elastomer capsule containing testosterone. On day 28 after pituitary grafting, LH levels were significantly suppressed in animals with a 2 or 1·5 cm testosterone implant. The weights of the accessory sex glands were not increased in the hyperprolactinaemic animals. These results show that in the male rat the inhibitory effects of hyperprolactinaemia on serum LH levels may be due to (1) increased sensitivity of the hypothalamic-pituitary axis to the negative feedback action of testosterone by prolactin and by the prolactin-stimulated corticosterone secretion and (2) stimulation of testicular testosterone secretion by prolactin, which can also explain the increased weights of the accessory sex glands. Even in the presence of high serum concentrations of corticosterone, stimulation of testicular testosterone secretion by prolactin was observed. J. Endocr. (1987) 113,111–116

scholarly journals The Effect of Zinc, Selenium, and Their Combined Supplementation on Androgen Receptor Protein Expression in the Prostate Lobes and Serum Steroid Hormone Concentrations of Wistar Rats

Nutrients ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 153 ◽  
Author(s):  
Adam Daragó ◽  
Michał Klimczak ◽  
Joanna Stragierowicz ◽  
Olga Stasikowska-Kanicka ◽  
Anna Kilanowicz
Keyword(s):  
Androgen Receptor ◽  
Protein Expression ◽  
Wistar Rats ◽  
Steroid Hormone ◽  
Serum Testosterone ◽  
Male Rats ◽  
Receptor Protein ◽  
Androgen Receptor Protein ◽  
Combined Administration ◽  
Combined Supplementation

Background: Zinc (Zn) and selenium (Se) play a well-documented role in cancer prevention (e.g., for prostate cancer), and their combined supplementation is often given as a recommended prophylactic agent. The aim of the study was to determine the influence of Zn and/or Se supplementation on the androgen receptor (AR) in the prostate lobes and the serum selected hormone concentrations; a hitherto unresearched topic. Methods: Male rats (n = 84) were administered with Zn and/or Se intragastrically for up to 90 days. The effects of administration on the tested parameters were checked after 30 and 90 days of administration and additionally, 90 days after the end of 90 day administration. Results: Zn alone leads to an increase in serum testosterone concentrations, while the protein expression of AR in both parts of the prostate increases. Combined administration of Zn and Se eliminates the effect of Zn, which may suggest that these two elements act antagonistically. Se supplementation alone results in the same level of AR protein expression in administration and 90 days after administration periods. Conclusion: This paper presents the first report of the influence of Zn and/or Se supplementation on the protein expression of AR in the prostate. Our findings seem to indicate that simultaneous supplementation of both elements may be ineffective.

Sexual dimorphism of hepatic 11β-hydroxysteroid dehydrogenase in the rat: the role of growth hormone patterns

1994 ◽  
Vol 143 (3) ◽  
pp. 541-548 ◽  
Author(s):  
S C Low ◽  
K E Chapman ◽  
C R W Edwards ◽  
T Wells ◽  
I C A F Robinson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Sexual Dimorphism ◽  
Mrna Expression ◽  
Hydroxysteroid Dehydrogenase ◽  
Male Rats ◽  
Total Daily Dose ◽  
Mrna Levels ◽  
Control Female ◽  
Gh Secretion ◽  
Repressive Effect

Abstract 11 β-Hydroxysteroid dehydrogenase (11β-HSD) catalyses the reversible metabolism of corticosterone to inert 11-dehydrocorticosterone. At least two isoforms exist. 11β-HSD-1, the first to be characterised and the only isoform for which a cDNA has been isolated, is highly expressed in liver, kidney and hippocampus. The activity of 11β-HSD in rat liver is higher in males, due to oestrogen repression of 11β-HSD-1 gene transcription in females. Sexual dimorphism in rodent liver proteins is frequently mediated indirectly via sex-specific patterns of GH release (continuous in females, pulsatile in males). We have now investigated whether this applies to 11β-HSD, using dwarf rats (congenitally deficient in GH) and hypophysectomised animals. 11β-HSD activity and 11β-HSD-1 mRNA expression in liver was significantly lower in control female than male rats (50% and 72% of male levels respectively). These sex differences in the liver were attenuated in dwarf rats, with both males and females showing similar levels of 11 β-HSD activity to control males. Administration of continuous (female pattern) GH to dwarf male rats decreased hepatic 11β-HSD activity (30% fall) and mRNA expression (77% fall), whereas the same total daily dose of GH given in the male (pulsatile) pattern had no effect on hepatic 11 β-HSD in female dwarf rats. Continuous GH also attenuated hepatic 11 β-HSD activity (25% fall) and 11β-HSD-1 mRNA expression (82% fall) in hypophysectomised animals. However, oestradiol itself suppressed hepatic 11β-HSD activity (25% fall) and 11β-HSD-1 mRNA expression (60% fall) in hypophysectomised rats. Renal 11 β-HSD activity showed no sexual dimorphism in control or dwarf rats, although overall activity was lower in dwarf animals. By contrast, 11β-HSD-1 mRNA expression was higher in male than female kidney in both control and dwarf strains. Neither GH pattern had any effect on 11β-HSD activity or 11β-HSD-1 mRNA levels in the kidney of dwarf rats, although continuous GH attenuated 11β-HSD activity (28% fall) and 11β-HSD-1 mRNA expression in kidney (47% decrease) in hypophysectomised animals. Oestradiol attenuated renal 11β-HSD-1 mRNA expression (74% fall) in hypophysectomised rats, but increased enzyme activity (62% rise) in the kidney. None of the manipulations had any effect on hippocampal 11 β-HSD activity or gene expression. These data demonstrate the following. (i) Sexual dimorphism of hepatic 11β-HSD is mediated, in part, via sex-specific patterns of GH secretion acting on 11β-HSD-1 gene expression. (ii) There is an additional direct repressive effect of oestrogen on hepatic 11β-HSD-1. (iii) Other tissue-specific factors are involved in regulating 11β-HSD-1, as neither peripheral GH nor oestrogen have effects upon hippocampal 11β-HSD-1. (iv) The regulation of 11β-HSD-1 mRNA expression in the kidney broadly parallels the liver. The lack of correlation between changes in expression of the 11β-HSD-1 gene and renal 11β-HSD activity reflects the presence of an additional gene product(s) in the kidney, the expression of which is largely independent of GH. Journal of Endocrinology (1994) 143, 541–548

scholarly journals Letrozole once a week normalizes serum testosterone in obesity-related male hypogonadism

2008 ◽  
Vol 158 (5) ◽  
pp. 741-747 ◽  
Author(s):  
Sandra Loves ◽  
Janneke Ruinemans-Koerts ◽  
Hans de Boer
Keyword(s):  
Hypogonadotropic Hypogonadism ◽  
Serum Testosterone ◽  
Free Testosterone ◽  
Total Testosterone ◽  
Male Hypogonadism ◽  
Serum Lh ◽  
Long Term Effect ◽  
Starting Dose ◽  
Severely Obese ◽  
Lh Secretion

ObjectiveIsolated hypogonadotropic hypogonadism (IHH) is frequently observed in severely obese men, probably as a result of increased estradiol (E2) production and E2-mediated negative feedback on pituitary LH secretion. Aromatase inhibitors can reverse this process. This study evaluates whether letrozole once a week can normalize serum testosterone in severely obese men and maintain its long term effect.DesignOpen, uncontrolled 6-month pilot study in 12 severely obese men (body mass index>35.0 kg/m2) with obesity-related IHH and free testosterone levels <225 pmol/l, treated with 2.5 mg letrozole once a week for 6 months.ResultsSix weeks of treatment reduced total E2 from 123±11 to 58±7 pmol/l (P<0.001, mean±s.e.m.), and increased serum LH from 4.4±0.6 to 11.1±1.5 U/l (P<0.001). Total testosterone rose from 5.9±0.5 to 19.6±1.4 nmol/l (P<0.001), and free testosterone from 163±13 to 604±50 pmol/l (P<0.001). Total testosterone rose to within the normal range in all subjects, whereas free testosterone rose to supraphysiological levels in 7 out of 12 men. The testosterone and E2 levels were stable throughout the week and during the 6-month treatment period.ConclusionLetrozole 2.5 mg once a week produced a sustained normalization of serum total testosterone in obese men with IHH. However, free testosterone frequently rose to supraphysiological levels. Therefore, a starting dose <2.5 mg once a week is recommended.

Oestrogenic regulation of testicular androgen production during development in the rat

1985 ◽  
Vol 105 (2) ◽  
pp. 211-218 ◽  
Author(s):  
B. A. Keel ◽  
T. O. Abney
Keyword(s):  
Serum Testosterone ◽  
Male Rats ◽  
Serum Prolactin ◽  
Testicular Function ◽  
Intact Male ◽  
Oestrogen Treatment ◽  
Testosterone Production ◽  
Age Related ◽  
Serum Lh

ABSTRACT The influence of age on the sensitivity of the testis to oestrogens was investigated. Intact male rats at 10, 25, 40 and 53 days of age were injected s.c. with vehicle, 5 or 50 μg oestradiol or diethylstilboestrol (DES)/100 g body wt twice daily for 2 days; the animals were killed 12 h after the last injection. Subsequently, the concentrations of testicular androgens and serum LH, prolactin, testosterone and androstanediol (5α-androstane-3α, 17β-diol) were measured. Testicular androgen production was determined in vitro in the presence or absence of human chorionic gonadotrophin (hCG) or dibutyryl cyclic AMP (dbcAMP). Androgens in the serum and testes displayed an age-related alternating pattern with androstanediol being the major androgen produced at 27 days of age. As a result of oestrogen treatment, serum LH concentrations were decreased while serum prolactin was increased. Serum testosterone was decreased by 36–55% in the 12-day-old group and further reduced by 95% of control values by day 55; serum androstanediol was less sensitive to oestrogen suppression. Testicular concentrations of both testosterone and androstanediol exhibited a marked reduction in 12-day-old animals as a result of oestrogen administration. These values were reduced by 85–95% at day 27 and remained suppressed even at 55 days. Basal production of testosterone was unaffected by oestrogen treatment in 12- and 27-day-old animals but was markedly decreased by day 42. Significant suppression of basal production of androstanediol was observed as early as day 12. Oestradiol treatment caused a significant reduction in hCG responsiveness of both androgens at days 12, 42 and 55. Oestrogen administration resulted in a significant (32–59%) decline in dbcAMP-responsive testosterone production in the 42-day group and a further suppression in the 55-day group. A marked inhibition of dbcAMP-stimulated androstanediol production was also observed in the 42- and 55-day groups. Testosterone production in response to dbcAMP was not significantly altered in the 12- and 27-day groups. With few exceptions the effects of oestradiol and DES on testicular function were similar. The data presented here suggest that the inhibitory effects of oestrogens become more pronounced as the animal approaches adulthood, that oestradiol and DES are similarly effective in regulating testicular function at all ages studied and that the production of both testosterone and androstanediol are suppressed by oestrogen administration. J. Endocr. (1985) 105, 211–218

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